Optical micrometers are well known in the prior art such as disclosed in coassigned U.S. Pat. No. 4,082,463, incorporated herein by reference, for a Calibrated Optical Micrometer. Therein, an optical micrometer utilizes a precisely dimensioned grate which is temporarily introduced into the optical path of the instrument within its zone of measurement. A beam of light is scanned through the zone of measurement and across the grate, and the information obtained therefrom is recorded in an electronic memory. Thereafter, articles subsequently placed within the zone of measurement are scanned by the beam and the information obtained thereform is compared against the calibration data to provide an accurate measurement of the article.
Coassigned U.S. Pat. No. 4,074,938, also incorporated herein by reference, describes an optical dimension measuring device employing an elongated, focused beam. Coassigned U.S. Pat. No. 4,097,158, also incorporated herein by reference, describes a half-maximum threshold circuit for an optical micrometer. However, these micrometers can only determine the diameter of an article to be scanned and cannot determine the profile of the article. "Profile" means a dimensional representation of an object viewed from the side, i.e., the external dimensions of the object and the relationship between the dimensions.
In general, profiles have been measured manually by employing "go/no-go" gauges which determine whether certain profile dimensions are within desired limits. Such manual measurements are time consuming and not highly accurate.